September 5, 2007 at 6:15 am #282
I posted this in another thread but decided to move it so that I dont detract from that topic. In the thread SPL meters were brought up and the effectiveness of LDCs. I had a cheap old Radio Shack meter so I dug it out and did some fast testing.
Ok, I dug out that old Radio Shack SPL meter. This is not high end equipment and it has probably been tucked away for at least 10 years now with no use.
Testing was done in my garage, not ideal but around here after dark it would have to do. There is allot of sound reflection from the hard walls and floor.
I started with a 200 bar fill. The gun was on a table facing away from the nearest wall. The meter was about 20 inches from the muzzle of the gun and about 5 inches from the center axis of the bore. The gun is a Talon SS with the 12″ barrel.
For a baseline I pulled out all the baffles and spacers in my gun. They are a very snug fit so the only way to get them out was to fire them out into my hand.
Future note. Wear gloves or wrap a towel around hand first. They come out friggin hard ).
My gun has a vented front bushing and the frame is vented under the hand guard as well.
I was going to see about plugging the bushing up in some way but I skipped that as I didnt want to have to take my gun apart to get whatever I used back out of there.
With the stock endcap on and with the vented bushing the gun was doing 100db consistently.
Next I put in one baffle and four of the baffle spacers that I use so that the baffle was about in the middle of the barrel and end cap. The SPL level had dropped 1 to 2 decibels from the baseline reading.
These are the baffles and spacers I used in my gun.
I then took out the two front spacers and slid another baffle inside. I put the two spacers I took out back in so now I had two baffles about two inches apart and about two inches from the end cap. Again, about a 2 decibel drop.
Finally, I took them all out and loaded all five into the gun with a spacer in between each. This is how I normally run my gun. It dropped another 6 or 7db for a total of around 10db total drop from the baseline.
Just so you know, every 3db you go up on the meter is twice as loud as it was before. Every 3db you can bring the sound down you are cutting the sound level in half.
Oh yeah, lead dust. When I pulled out my baffles the baffle closest to the barrel had a fairly solid coating of lead dust on it. It wasnt on the cone itself but on that outer ring where the cone stops. The baffle closest to the end cap had no dust at all that I could see. The other baffles coating was graduated in dust levels from darkest to lightest the closer you got to the barrel.
This doesnt really compare to you guys with the longer shrouds on your gun as this was all contained inside the TSS frame. It gives you some idea on how stripper cones work in these shrouds though, I hope.September 5, 2007 at 6:20 am #23920yParticipant
Good write up !
I think you might see a drop if you put some scotch brite between the bushings.
Has anyone used a sound meter on an empty tank to see much much noise is from the hammer/valve/tank? I think I had some sound meter software on the PC in my basement has part of an oscilloscope software package so I might try this out myself.September 5, 2007 at 6:29 am #23922
Anything has to be better than that Radio Crap I used. The mic is the most important piece of an SPL meter.
Since you pointed it out I should mention that my hammer does have a rubber flat washer on the back side to reduce hammer slap.
One other thing is that along with sound reduction these types of baffle systems also change the pitch of the discharge. Stock it is a loud bark with a metallic bite to it. After the LDC it changes to more of a muted thud type of sound.September 5, 2007 at 6:41 am #23924yParticipant
Mine is far from silent, but its a long “whoosh” as opposed to a single distinct .22lr type concussion, for plinking in the yard thats nearly as important as the noise reduction.. for hunting I’d rather the thing be silent, but I cant have that and will just have to keeop making small progress here and there.
Hammer ping is annoying me, even though it isnt that big a deal noise wise I just dont like it…. need to work on that along with dropping the power a bit to around 20 fpe to get it a little queiter.September 5, 2007 at 12:35 pm #23929rabbitsParticipant
great write up and great wiork mate welldone ..i wish i could do some work like that but i think i,m safer sticking to the wood lol 😀September 5, 2007 at 1:40 pm #23933teflontronParticipant
I have a big decision to make soon: what to do about a .25 Condor. I can’t stand the look of a frame extender and love the look of a fat Silencer, but don’t really want to break any Laws.
Stripper Cones are very effective, especially if combined with other materials such as sound deadening foam etc.September 8, 2007 at 8:31 pm #24088airtrampParticipant
Hi Teflon Tron, my thought is exactly the same. The regular frame extender doesn’t make it look like a bull barrel but rather fat and cumbersome, not to mention too loooong. Seems like the only way to make it legal and pretty is a short barrel and LDC within the frame.September 8, 2007 at 10:46 pm #24095
I feel the same way. I would love to have a longer barrel with an LDC on the end of it. I dont much care for the long shroud extensions that Ive seen. The way I run my baffles there is no way it could be pulled out and used on a firearm so I think (hope) that Im ok legally.
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